EA037963B1 - Method for measuring wet friction of hair - Google Patents

Abstract

A method of measuring wet friction of hair, using a system comprising: i) a friction probe, having a contact surface, said probe fitted with a weight in the range of from 10 to 500 g; ii) a means for securing the bundle of hair; and iii) a water bath; wherein the friction probe is connected to a texture analyser; said method comprising the steps of: i) providing a bundle of hair fibres; ii) aligning the hair fibres; iii) securing the bundle of hair fibres; iv) immersing the bundle of hair fibres under water in the water bath; v) contacting the hair fibres with the contact surface of the friction probe, which is fitted with the weight; vi) moving the probe along the hair fibres; and vii) recording the friction generated under step vi); wherein steps v)-vii) take place under water; and wherein steps vi)-vii) are repeated until a constant value is obtained, without lifting the probe from the hair.

Description

Explore techniques

The present invention relates to a method for measuring the friction of wet hair, in particular with respect to hair that has been treated with a hair care composition, and to comparisons of the friction of hair treated with different care agents.

Hair Friction Assessment provides information on the condition of the hair, which can be influenced by factors such as cuticle lift, cuticle rupture, surface erosion and deposition of materials on the hair surface. Information on the effectiveness of care products and friction-reducing materials can also be provided. This, in turn, provides an effective selection of products that are appropriate for a specific hair condition.

There are many systems and methods available for such assessments.

In Chemical and Physical Behavior of Human Hair, by Clarence R. Robbins, 4th edition, Springer; pp. 439-440, provides a summary of known methods under the heading Methods for Measuring Friction on Hair Fibers, including a method attributed to Scott and Robbins, which involves attaching a hair fiber root to a load cell of an instrument to Instron tensile strength tests, tip loading and partial wrapping around two spindles. The spindles are attached to the crosshead and, as they are moved downward relative to the fiber, frictional tension is recorded. Friction is believed to vary with the speed of relative frictional motion, with large differences shown between care products at low speeds of relative frictional motion. Using this method, the modeling of combing dry hair and hair immersed in water is disclosed.

In US 20090324529, the frictional force of hair is measured using a texture analyzer (TA), in which the composition is applied to 10 g of a hair sample. After spreading the composition on the hair sample, and before and after rinsing with water, the friction force between the hair sample and the polyurethane liner is measured using a texture analyzer.

The inventors in EP1652555 disclose the measurement of friction using a texture analyzer and a friction sensor in the form of a stainless steel cylinder covered with a rubber material. A lock of hair is placed on a texture analyzer and the hair fibers are smoothed out by combing before being fixed in a flat configuration. The friction sensor is placed on the hair and a load of approximately 560 g is applied to the friction contact. The sensor is moved along the hair at a speed of 10 mm s ^-1 to measure the friction between the sensor and the hair. The method is used to evaluate the frictional properties of hair treated with various hair conditioners.

However, these prior art methods are not sensitive to sufficiently discriminate some of the care products. The inventors have found that the known methods do not allow the consumer to differentiate between products, in particular during the rinsing step.

The inventors have found that the measurement of the friction of a hair bundle under water, which uses a friction sensor equipped with a weight, attachment means and a water bath connected to a texture analyzer, where the sensor is repeatedly moved along the hair fibers until a constant value is reached, provides unexpectedly accurate measurement.

Disclosure of invention

According to a first aspect of the present invention, there is provided a method for measuring fluid friction of hair using a system comprising:

i) a friction sensor having a contact surface and equipped with a weight of 10 to 500 g;

ii) means for securing the hair bundle; and iii) a water bath;

moreover, the friction sensor is connected to the texture analyzer; and the method includes the steps:

i) providing a bundle of hair fibers;

ii) aligning the hair fibers;

iii) anchoring the hair fiber bundle;

iv) immersing the bundle of hair fibers under water in a water bath;

v) ensuring the contact of the hair fibers with the contact surface of the friction sensor, which is equipped with a weight;

vi) moving the sensor along the hair fibers and vii) recording the friction generated in step vi);

moreover, stages v) - vii) are performed under water; and steps vi) - vii) are repeated until a constant value is reached, without lifting the probe from the hair.

Thus, the inventors have found that very small differences in friction with consumer data are perceived.

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Brief Description of Drawings

Embodiments of the invention will be described below with reference to the following non-limiting drawings, in which:

in fig. 1 is a perspective view of a system for use in accordance with the method of the present invention;

in fig. 2 is a dipping friction profile for treated hair obtained using the method of the present invention.

The system of FIG. 1 contains a friction sensor (1) having a contact surface (2) that contains a surfactant equipped with a weight (3) connected to a texture analyzer (4); and said figure shows a bundle of hair fibers (5) clamped in two positions along its length by a clamp (6); moreover, the clamp and the friction sensor are located in the water bath (7) below the filling line (8).

Implementation of the invention

Way

Preferably, steps vi) to vii) of the method are repeated without lifting the probe from the hair until a constant value is reached. Preferably steps vi) to vii) are repeated 15 to 100 times, more preferably 20 to 60 times, most preferably 30 to 50 times.

Preferably, steps iv) to vi) of the method are carried out without opening the securing means.

The expression movement of the sensor along the hair fibers in step iv) should be understood to mean that the sensor slides along the hair fibers from one end to the other end, while the hair fiber is stationary during the sliding of the sensor.

The hair fibers are aligned prior to contact with the sensor. This is preferably achieved by brushing the hair with a comb or brush.

A method for evaluating the effectiveness of reducing friction with a hair care composition includes the step of treating a bundle of hair fibers with the first hair care composition prior to performing the method according to the first aspect of the present invention. As used herein, the term treatment is to be understood to mean the application of a hair composition to a bundle of hair fibers. In a preferred embodiment, the hair fibers are washed and / or rinsed prior to application of the hair composition. Preferably, the hair fibers are rinsed after application of the hair composition, but before being fixed to said agents.

The method may further include the step of treating the bundle of hair fibers with the second hair care composition, performing the method of the first aspect of the invention and comparing the friction of the hair treated with the first hair care composition with the friction of the hair treated with the second hair care composition.

Hair Fiber Bundle

The hair fiber bundle is preferably bonded or glued at one end. Preferably, the hair fiber bundle is a strand, preferably containing 50 to 5000 hair fibers, more preferably 500 to 2000 hair fibers.

Preferably, the weight of the hair strands is from 1 to 20 g, more preferably from 2 to 10 g. Preferably, the length of the hair strands is from 10 to 50 cm, more preferably from 15 to 30 cm.

Friction sensor

The friction sensor has a contact surface that contacts the hair during use. The contact surface is preferably the outer surface of the friction sensor.

Preferably, the friction sensor comprises a rubber material, preferably synthetic rubber, more preferably neoprene.

Preferably, the contact surface of the friction sensor contains a surfactant. Preferably, the level of surfactant on the friction sensor is 10 to 1500 μg / cm ² , more preferably 50 to 1000 μg / cm ² , even more preferably 80 to 500 μg / cm ² , more preferably 100 to 200 μg / cm ² .

The mass of the friction sensor itself is approximately 20 to 100 g, preferably 40 to 80 g, more preferably 60 g. The friction sensor is equipped with a weight of 10 to 500 g, preferably 50 to 300 g, more preferably 100 to 200 g. The weight of the load ensures good contact between the sensor and the hair.

Preferably, the friction sensor is a stainless steel cylinder covered with said rubber material.

Surfactant can be added to the sensor by treatment with an aqueous surfactant and drying.

A preferred method is that, prior to use, the sensor is first washed with an aqueous surfactant composition having a surfactant concentration of 5 to 25 wt% based on the total weight of the aqueous surfactant composition and rinsed with water. Then the sensor is soaked in a dilute aqueous solution of a surfactant 2 037963 active substance with a concentration of 10 to 1500 ppm. and dried.

The aqueous surfactant composition has a concentration of 5 to 25 wt%, preferably 8 to 20 wt%, based on the total weight of the aqueous surfactant composition, for example 14 wt%.

After treatment with the aqueous surfactant composition, the sensor is rinsed with water (preferably until the slippery sensation disappears) before soaking in a dilute aqueous surfactant solution of 10 to 1500 ppm, preferably 50 to 500 ppm. etc., more preferably from 80 to 200 ppm, for example 140 ppm, preferably within 30 seconds to 5 minutes, more preferably from 1 to 3 minutes.

The sensor is then dried, preferably for 10 minutes to 3 hours, more preferably 1.5 to 2.5 hours.

Preferably, the surfactant in both the aqueous surfactant composition and the dilute surfactant solution is an anionic surfactant, preferably sodium laureth sulfate (SLES).

Preferably, the sensor is first washed with an aqueous anionic surfactant composition having a concentration of 5 to 25 wt% and rinsed with water, then soaked in a dilute aqueous surfactant solution at a concentration of 10 to 1500 ppm. for 1 to 3 minutes and dried for 1.5 to 2.5 hours.

Anchoring means

The bundle of hair fibers is secured with anchoring means. Preferably, the securing means are a clip. Preferably, the hair is secured at two positions along its length.

Water bath

The securing means and friction sensor are located in the water bath below the fill line. Preferably the water is warm, preferably between 25 and 40 ° C.

Texture Analyzer (TA)

Any suitable texture analyzer can be used, for example the TA.XT2i texture analyzer available from Stable Micro Systems, Surrey, UK. The texture analyzer reads the friction of the hair through the sensor.

The sensor is connected to the texture analyzer.

Without wishing to be bound by any theory, it is believed that the present invention works in the area between boundary lubrication and hydrodynamic lubrication. This area itself is commonly referred to as elastohydrodynamic lubricant and mixed lubricant. In the field of hydrodynamic lubrication, the fluid completely isolates the friction surfaces (sensor and hair) and only internal fluid friction determines the tribological characteristics. In the region of boundary lubrication, the hydrodynamic action of lubricants (eg hair composition left on the fibers) does not significantly affect tribological properties. In contrast, in the area of mixed lubrication, fluid (eg, fluid viscosity), pressure, hard surfaces are influencing factors. The inventors have observed that the system according to claim 1 can be used to differentiate even small differences in hair friction resulting from the use of different hair care compositions. In addition, the difference appears to correlate well with consumer perception.

Hair care composition

Preferred hair care compositions for use in the methods of the present invention are rinse compositions.

Preferred hair care compositions are selected from shampoo, hair conditioner, and hair mask.

Rinse conditioners for use in accordance with the present invention are conditioners that are typically left on wet hair for 1 to 2 minutes before rinsing.

Hair masks for use in accordance with the present invention are care products that are typically left on the hair for 3 to 10 minutes, preferably 3 to 5 minutes, more preferably 4 to 5 minutes, before being rinsed off.

Care compositions for use in the method of the present invention preferably contain conditioning agents. Conditioning agents are preferably selected from cationic surfactants alone or as an additive.

Cationic surfactants used in compositions for use in the method of the present invention contain hydrophilic amino or quaternary ammonium moieties that are positively charged when dissolved in an aqueous composition.

Examples of suitable cationic surfactants are those corresponding to the formula:

[N (Ri) (R ₂ ) (R ₃ ) (R ₄ )] ⁺ (X) -,

- 3037963 in which R1, R2, R3 and R4 are independently selected from (a) an aliphatic group of 1 to 22 carbon atoms or (b) an aromatic, alkoxy, polyoxyalkylene, alkylamido, hydroxyalkyl, aryl or alkylaryl group having up to 22 carbon atoms ; and X is a salt-forming anion, for example selected from halogen (eg, chloride, bromide), acetate, citrate, lactate, glycolate, nitrate phosphate, sulfate and alkyl sulfate radicals.

Aliphatic groups may contain, in addition to carbon and hydrogen atoms, ether bonds and other groups such as amino groups. Longer chain aliphatic groups, such as those with about 12 carbon atoms or greater, may be saturated or unsaturated.

The most preferred cationic surfactants for compositions for use in the process according to the present invention are monoalkyl quaternary ammonium compounds in which the alkyl chain length is from C ₁₆ to C ₂₂ .

Suitable examples of such materials correspond to the formula

[N (R ₅ ) (Kb) (K ₇ ) (K ₈ )] ⁺ (X) 'in which R5 is a hydrocarbon chain containing from 16 to 22 carbon atoms, or a functionalized hydrocarbyl chain with 16-22 carbon atoms, and containing ether, ester, amido or amino groups present as substituents or as bonds in the radical chain, and R ₆ , R ₇ and R8 are independently selected from (a) hydrocarbyl chains with 1-4 carbon atoms, or (b ) functionalized hydrocarbyl chains having from 1 to 4 carbon atoms and containing one or more of aromatic substances, substances based on esters, esters, amido or amino groups present as substituents or as bonds in the radical chain, and X is a salt-forming anion, for example selected from halogen (eg chloride, bromide), acetate, citrate, lactate, glycolate, nitrate phosphate, sulfate and alkyl sulfate radicals.

The functionalized hydrocarbyl chains (b) may suitably contain one or more of hydrophilic substances selected from alkoxy (preferably C ₁ -C ₃ alkoxy), polyoxyalkylene, alkyl ether, and combinations thereof.

Preferably the R1 hydrocarbon chains have from 16 to 22 carbon atoms. They can be obtained from starting oils that contain substantial amounts of fatty acids having the desired hydrocarbyl chain length.

Typical monoalkyl quaternary ammonium compounds of the above general formula for use in compositions for use in a process according to the present invention comprise:

(i) cetyltrimethylammonium chloride (commercially available, for example, as Dehyquart from BASF); trimethylammonium chloride behenyl (commercially available, for example, as Incroquat ™ Behenyl, from Croda);

(ii) compounds according to the formula

[N (Ri) (R ₂ ) ((CH ₂ CH ₂ O) _x H) ((CH ₂ CH ₂ O) _y H] ⁺ (X) in which x + y are an integer from 2 to 20;

R1 represents a hydrocarbyl chain having from 16 to 22 carbon atoms and containing ether, ester, amido or amino groups present as substituents or as bonds in the radical chain;

R2 is a C1-C3 alkyl group or a benzyl group, preferably methyl, and

X is a salt-forming anion, for example selected from halogen (eg, chloride, bromide), acetate, citrate, lactate, glycolate, nitrate phosphate, sulfate, methyl sulfate and alkyl sulfate radicals;

(iii) compounds according to the formula

[N (Ri) (R ₂ ) (R ₃ ) ((CH ₂ ) _n OH)] ⁺ (X) in which n is an integer from 1 to 4, preferably 2;

R1 is a hydrocarbyl chain having 16 to 22 carbon atoms;

R2 and R3 are independently selected from C1-C3 alkyl groups and are preferably methyl, and

X is a salt-forming anion, for example selected from halogen (eg, chloride, bromide), acetate, citrate, lactate, glycolate, nitrate phosphate, sulfate, alkyl sulfate radicals.

Mixtures of any of the cationic surfactant compounds described above may also be suitable.

Examples of suitable cationic surfactants for use in hair compositions for use in the method of the present invention include cetyltrimethylammonium chloride, behenyltrimethylammonium chloride, cetylpyridinium chloride, tetramethylammonium chloride, tetraethylammonium chloride, dimethylammonium chloride, octylammonium chloride , octyldimethylbenzylammonium chloride, decyldimethylbenzylammonium chloride, stearyldimethylbenzylammonium chloride, didodecyldimethylammonium chloride, dioctadecyldimethylammonium chloride, tallotrimethylammonium chloride, cocotrimethylammonium chloride, and the corresponding hydrocotrimethylammonium chloride. In addition, suitable cationic surfactants include those materials bearing the CTFA designations Quaternium-5, Quaternium-31, Quaternium-98 and Quaternium-18. Mixtures of any of the above materials may also be suitable. A particularly useful cationic surfactant is cetyltrimethylammonium chloride, commercially available, for example as DEHYQUART, from Henkel.

The level of cationic surfactant is preferably from 0.01 to 10, more preferably from 0.05 to 5, most preferably from 0.1 to 2% by weight, based on the total weight of the composition.

A preferred conditioner comprises a conditioning gel phase. Such air conditioners and methods for their production are described in documents WO2014 / 016354, WO2014 / 016353, WO2012 / 016352 and WO2014 / 016351. A preferred hair conditioning composition of this type contains 0.4 to 8% by weight of a fatty alcohol having 8 to 22 carbon atoms, 0.1 to 2% by weight of a cationic surfactant component, water, the composition providing a weight for pulling from 1 to 250 g of hair treated with a conditioning composition. The pull mass is the mass required to pull a bundle of hair through a comb or brush.

Conditioning compositions may also contain other ingredients, if desired. Such ingredients include, but are not limited to, fatty material, precipitated polymers, and conditioning agents.

Conditioning compositions preferably additionally contain fatty materials. It is believed that the combined use of fatty materials and cationic surfactants in conditioning compositions should be particularly preferred because it results in the formation of a structured layered or liquid crystalline phase in which the cationic surfactant is dispersed.

By fatty material is meant a fatty alcohol, an alkoxylated fatty alcohol, a fatty acid, or a mixture thereof.

Preferably, the alkyl chain of the fatty material is fully saturated.

The presented fatty materials contain from 8 to 22 carbon atoms, more preferably from 16 to 22. Examples of suitable fatty alcohols include cetyl alcohol, stearyl alcohol, and mixtures thereof. The use of these materials is also preferred as they contribute to the conditioning properties of the compositions in general.

Alkoxylated (eg, ethoxylated or propoxylated) fatty alcohols having from about 12 to about 18 carbon atoms in the alkyl chain can be used in place of or in addition to fatty alcohols. Suitable examples include ethylene glycol cetyl ether, polyoxyethylene (2) stearyl ether, polyoxyethylene (4) cetyl ether, and mixtures thereof.

The level of fatty material in the conditioners is suitably from 0.01 to 15, preferably from 0.1 to 10, more preferably from 0.1 to 5% by weight, based on the total weight of the composition. The weight ratio of cationic surfactant to fatty alcohol is suitably from 10: 1 to 1:10, preferably from 4: 1 to 1: 8, optimally from 1: 1 to 1: 7, for example 1: 3.

In addition, the conditioning ingredients contain esters of fatty alcohols and fatty acids such as cetyl palmitate.

The conditioning composition for use in accordance with the present invention may comprise a micellar structured liquid.

The pH of the conditioner containing the present composition is preferably 3 to 5. More preferably, the pH of the composition is 4.5 to 5.5.

When the pH of the composition is less than 3.10, it is preferred that it is in the form of an intensive conditioning mask.

In addition, the conditioning ingredients contain conditioning oils, preferably selected from coconut oil and olive oil.

The present invention will be shown below with reference to the following non-limiting examples:

Example 1 Hair care composition prior to friction analysis.

A conditioning hair treatment composition was prepared and used prior to friction analysis using the method of the present invention. The composition is shown in Table 1.

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Table 1. Compositions of conditioner A

International nomenclature cosmetic ingredients Active level BUT Stearamidopropyldimethylamine 100 one Behentrimonium chloride 70 one Cetearyl alcohol 100 4 Preservative 55 0.1 Sodium chloride 100 0.1 Perfume 100 0.6 Preservative 100 0.04 Water 100 Up to 100

Composition A was prepared by adding cationic surfactants to the fatty alcohol and stirring at 85 ° C. Water was gradually added to this mixture, usually at 55 ° C, so that the temperature of the mixture was 60 ° C. The specified temperature was maintained for 30 minutes with stirring. Then the mixture was cooled to ambient temperature by adding more water and other ingredients at ambient temperature and, if necessary, using external cooling and stirred.

Example 2 Hair care with composition A prior to friction measurements with a structure analyzer according to the present invention.

The hair used was dark brown European type hair in bundles weighing 5 g and 6 inches (15.24 cm) in length.

The hair was treated with Composition A as follows.

First, the hair was treated with a cleansing shampoo using the following method.

The hair fibers were kept under running water for 30 s, the shampoo was applied in an amount of 0.1 ml of shampoo per 1 g of hair and rubbed into the hair for 30 s. Excess foam was removed by holding under running water for 30 seconds and the shampooing step was repeated. The hair was rinsed under running water for 1 min.

Then, the wet hair was treated with conditioner A using the following method.

Conditioner was applied to wet hair in an amount of 0.2 ml of conditioner per gram of hair and massaged into hair for 1 minute. The hair was rinsed under running water for 1 min, and the excess water was removed.

Example 3. Measurement of friction of hair treated with composition A.

Friction was measured using the apparatus and method of the present invention as follows.

Friction was measured using a TA.XT2i structure analyzer available from Stable Micro Systems, Surrey, UK. The friction gauge was a stainless steel cylinder covered with a rubber material. The frictional contact load was approximately 138 g. In use, a contact area between the outer surface of the friction sensor and the hair of approximately 1.0 cm ² was achieved.

Surfactant was added to the sensor as follows.

The sensor was first washed with an aqueous sodium laureth sulfate (SLES) composition at a concentration of 14 wt% based on the total weight of the aqueous surfactant composition and rinsed with water. Then the sensor was soaked in a dilute sodium laureth sulfate solution having a concentration of 14 ppm for 2 minutes and then dried for 2 hours.

The methodology used to evaluate the frictional properties of hair treated with hair conditioner A was as follows.

A lock of hair was securely attached to the texture analyzer, with the hair fibers aligned by combing before being fixed in a flat configuration. The hair was immersed in a water bath. A friction sensor was placed on the hair and moved along the hair at a speed of 10 mm s ^-1 to measure the friction between the sensor and the hair. The measurement was repeated 30 times.

The friction values shown below represent the friction hysteresis in g / mm units obtained by integrating the total measured friction force over the entire distance traveled by the sensor, along and against the cuticle.

The measured immersion friction, at 30 repetitions, on hair tufts treated with Conditioner A is shown in Table 2 and shown graphically in FIG. 2.

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Table 2. Immersion friction measurements for hair treated with conditioner A, 1 to 30 repetitions

The data from Table 2 are presented graphically in FIG. 2.

FIG. 2 shows the immersion friction profile for hair treated with Conditioner A at 30 repetitions.

It is clear that friction levels obtained at a true constant value, after only a few measurements, are much more accurate and useful in comparison than friction measurements that were not repeated until a constant value.

Example 4: Measurement of friction with a sensor equipped with various weights.

Composition A was used to treat hair fibers as described in Example 1. All sensors contain a surfactant prior to use. All other experimental details are the same as described in example 3, except that the sensor is equipped with weights of 0 g (unweighted), 138 g and 1000 g, respectively.

After 30 measurements, the average friction recorded for the sensor equipped with a weight of 138 g was 133.18 g / mm, which is in good agreement with the data obtained in table. 2. It was found that the average friction recorded for a sensor equipped with a 1000 g weight was artificially increased to 216.22 g / mm. In addition, this high friction made it difficult to repeat the measurements, as the hair constantly slipped out from under the clip and then floated above the water. On the other hand, the lack of load on the sensor significantly reduced friction. No important data was recorded.

Claims (7)

CLAIM 1. A method for measuring fluid friction of hair using a system containing: i) a friction sensor (1) having a contact surface (2) and equipped with a weight (3) weighing from 10 to 500 g; ii) means (6) for securing the hair bundle (5); and iii) a water bath (7); moreover, the friction sensor is connected to the texture analyzer (4); and the method includes the steps: i) providing a bundle of hair fibers (5); ii) aligning the hair fibers (5); iii) anchoring the hair fiber bundle (5); iv) immersing the bundle of hair fibers (5) under water in a water bath (7); v) ensuring the contact of the hair fibers (5) with the contact surface (2) of the friction sensor (1), which is equipped with a weight (3); vi) moving the sensor (1) along the hair fibers (5) and vii) recording the friction generated in step vi); moreover, stages v) - vii) are performed under water (8); and steps vi) - vii) are repeated until a constant value is reached, without lifting the sensor (1) from the hair (5). 2. A method according to claim 1, comprising the step of treating the hair fiber bundle (5) with the first hair care composition. 3. A method according to claim 2, comprising the steps of treating the hair fiber bundle (5) with the second hair care composition and comparing the friction of the hair treated with the first hair care composition against the friction of the hair treated with the second hair care composition. 4. A method according to any one of the preceding claims, wherein steps vi) to vii) are repeated 15 to 100 times. 5. A method according to any of the preceding claims, wherein the sensor (1) contains a surfactant. 6. A method according to claim 5, wherein the level of surfactant on the friction sensor (1) is between 10 and 1500 µg / cm ² . 7. A method according to any of the preceding claims, wherein the friction sensor (1) comprises a rubber material.